How can i model x^3/x^2>=-2 constraint in cvx?

Nonconvex
1

hi i simplized my problem in very long model in a short form
i have error for this x^3/x^2>=-2 constraint. i try pow_p and pow_p(x,3)+2*(x^2)>=0 but the errors remain like: {positive convex}+{positive convex}
{positive convex}>=0
is there any way to handle it in cvx

2
3

hi MCG thanks but i read it before. if i change variables like s>=x^3 and v>=x^2 and then change constraint to s/v>=-2 and then to s+2v>=0. it works. but is it true or not change? i dont know.if you know it is a true transform please verify that. if it is a false operation please mention that.
thanks again

4

Sorry, this is a software forum not a modeling forum. But here’s what I want to know: you have x^3/x^2\geq -2; why aren’t you just canceling that fraction and using x\geq -2?

A proper reading of the FAQ would have made it clear why your pow_p attempt failed, and why you shouldn’t have bothered to try it.

5

Thanks again but in real model it isnt.I simpelized it.it has 24 x in up the fraction and 24 x in down of it. Every x has own cofficient.x^3 refer to skewness and x^2 refer to variance in a portfolio selection model. I regret that i must give up cvx.
But thanks for your time consuming

6

Indeed, it sounds like your problem is not convex, so CVX is not your tool.